The Acquabianca fortress, whose acquired name was taken from the homonymous ditch, already known at least since the first half of the thirteenth century, is a hill fortification dating back to the Middle Ages built for defense and supremacy over the valley of the Topino river. The name was originally "Fortellitium Agnani", and it constituted a link in the Trinci defensive line. Until 1969 it was in a state of ruins, and in that year it was renovated by the Recchi using "the ancient stones" (as a walled inscription states); despite the excellent restoration work carried out, it now appears completely invaded by climbing plants, which had once been planted to decorate the residence; in fact the complex suffered extensive damage in the 1997 earthquake, and was abandoned again.